Logging in an unprotected part of the Bialowieza forest, the last remaining primeval forest in the European lowlands. Photograph: David Levene for the Guardian

It is a spectacle of savage beauty: splintered stumps and trunks lie like battlefield corpses between soaring oak and lime trees. Ochre-fringed bracket fungus feasts on the dead wood, while the first green shoots of spring pierce the leaf mold, amid the tracks of wolves and bison.

For ecologist Janusz Korbel, standing in the forest he loves and surrounded by decaying logs and branches, it is this life springing from death that is at the heart of this untouched place. "It's a kind of Eden," he says. "It was not created by humans."

The Białowieża forest is a time capsule, protected for centuries by Polish kings and Russian tsars as a royal hunting ground. To walk among the giant, slender trees – the tallest in Europe – is to glimpse the primeval forest that once blanketed all of the continent's lowlands. "It began about 8,000 years ago and has existed since then without any meaningful interference from people," says Korbel. But Białowieża is the last significant fragment of that vast forest, and while a 10 sq km wood is fully protected, a mighty battle is being fought over the 84% of the forest that lies outside the national park.

It is an almost biblical battle of philosophies, pitting those who believe nature has to be actively managed to prosper in the 21st century, and those who think nature can only be truly natural if left alone. Korbel is firmly in the latter camp: "This forest has lived for thousands of years without humans."

Opposing him is the powerful state forestry service, which manages 30% of all Poland's land and exerts deep local influence. "To keep the habitat in its proper state it needs to be managed and foresters try to manage natural forces," says regional director Marek Maslowski. "It is necessary to cut some trees to help nature work faster."

The key question today is whether the successful protection the national park provides should be extended, to protect the ancient trees and myriad species that live outside its boundaries. For example, white-backed woodpeckers, whose resonant knocking booms over the spring chatter, have lost 30% of their population in the past 20 years in forestry-managed areas.

"This is the best moment in many years for change," says Robert Cyglicki, director of Greenpeace Poland, as we survey a clear-felled copse. There is a Polish general election in October, the Polish presidency of the European Union in July 2012, as well as the drafting of a new forest management plan and a crucial change in legislation to ease the extension of national parks. The latter was prompted after Greenpeace collected 250,000 petition signatures in November and follows its three-day occupation of the environment ministry roof in August. The forest has been a Unesco world heritage site since 1979.

In coal-dependent Poland environmentalists are rare, with little national sympathy for action on climate change. Adam Wajrak, nature correspondent for Poland's biggest daily paper Gazeta Wyborcza and Białowieża resident, says: "Polish people are very different to those in the west. They don't save energy. But they are very connected to nature. Most of us have grandparents in the countryside, some farmers, some foresters, and spend holidays there. I am surprised how much emotion comes out. If they tried to cull wolves here, as they did in Sweden, there would be demonstrations in the street."

But that connection to the land cuts both ways. Unlike in the UK, where broad public protest overturned government plans to sell off England's national forests, there is entrenched local opposition to enlarging the national park. The neat woodpiles by the timber homes in the villages around Białowieża, and the smell of woodsmoke, show the visceral connection of the people to the forest. As well as heating their homes through winters in which temperatures plummet below zero for months, many have worked as foresters for generations.

Near the village of Sorocza Nóżka, foresters are clear felling a stand of trees planted 80 years before. Environmentalists do not oppose the cutting of earlier plantations, but these areas of low ecological value blend into more natural forest. Within earshot of the chainsaws there are mighty oaks, some 140ft tall, and abundant evidence of the woodpeckers that, with owls, eagles and other birds, attract thousands of British birdwatchers every year.

The forestry foreman, who asked not to be named, is blunt in his opposition to enlarging the national park and allowing its natural wonders to reclaim the entire 60,000 hectares (148,200 acres) of the Białowieża forest on the Polish side of the Belarus border. "Look, the ecologists and campaigners get their salaries for what they do, I get mine for what I do. I employ 20 men, 60 people with their families, and they can't imagine any other job," he says. "If you had been here two days ago, you would have seen the villagers fighting for the small amount of wood we can give. I said 'go and ask the ecologists for your wood'."

Most environmentalists agree that a small amount of timber could be taken sustainably from outside the current national park, but only if rules such as protecting trees more than 100 years old are observed. Adam Bohdan, of the campaign group Workshop for All Beings, spends hours in the forest using GPS to record rule breaches, such as felling trees with hollows used by birds to nest, or felling in the breeding season.

As we leave Sorocza Nóżka, he finds a bronze beetle larva nestled in the bark of a log stacked by the track. "That's Cucujus cinnaberinus," he says of the 15mm creature, which like many of the 8,000 insect species in Białowieża specialises in eating dead wood. "It's protected under the EU habitats directive, and is already extinct in some countries." His GPS-tagged photo, sent to the nature protection unit, should prompt officials to return the dead wood to the forest. "If it is not stolen in the night," he adds. To date, there have been no prosecutions for breaking management rules, but Bohdan was himself taken to court last year, unsuccessfully, for collecting a small sample of a new lichen for scientific identification. "They are getting desperate," says Cyglicki. "They want to try to prevent ecologists and activists going deep into the forest."

The dead wood is vital to life in the most natural part of the forest, the strictly protected zone within the national park where the only entry is on foot and with a permit and a guide. Korbel says almost half of all the wood in the forest is dead, 10 times more than in managed forests, and that half the 12,000 species depend on decaying logs. In managed forests, the dead wood is removed by foresters who see it as a sign of an ecosystem in danger, or as a fire risk. Such forests are mere gardens, Korbel scoffs, no more natural than a manicured lawn. It is the balanced rhythm of life and death, Korbel says, which supports a full ecosystem, headed by the largest herd of European bison in the world, and featuring wolves, lynx and eagles that keep the numbers of deer, moose, boar and beavers in proportion.

Foresters, of course, disagree and nowhere more vehemently than over the bark beetle. This modest-looking insect strikes terror into the hearts of woodmen. The spruce stripped of their bark die quickly and lie scarred on the forest floor, the trunks resembling the backbones of slain giants.

Zdzisław Szkiruć, director of the Białowieża national park, gives an example from another national park he previously worked in. "The bark beetles struck and huge areas were covered by dead spruce. If they were cut and replanted with the same species, in 50 years we will have proper forest. But if we left the dead trees in the forest, it will take 300-400 years for the same type of forest to come back. So some people say we should kickstart nature, but some say we can wait for nature to act. This is the key discussion point."

Ecologists say cutting and replanting makes sense in conventional, managed forests but not in the unique primeval forest of Białowieża. "In nature, all is connected and the beetles – a food for birds – attack only the weakest trees, helping to establish good relations between all the species," says Korbel.

Like Szkiruć, the person with the ultimate responsibility for the Białowieża forest, environment minister Andrzej Kraszewski, wants an extension of the existing protections. "I will try to establish protection over the whole area, but as a first shot I would like to do another 12,000-14,000 ha," he told the Guardian. "There are two obstacles: the opinion of the local communities – they have very firm opinions that they can exploit this area as they have for hundreds of years – and the opinion of the forestry service, who believe there is no harm in exploiting the forest in a modest way. I have to convince both of them."

An offer by a previous environment minister of 100m zlotys (£22m) for local enterprise in return for a 20% extension of the national park was rejected. "Local politicians think that if they accept money from the ministry of environment, they will not be elected next time," says Kraszewski. "I intend to start negotiations with the local societies from scratch."

While the latest efforts to overcome the mistrust of local citizens play out, the scientists prepared to speak out continue to protest against the gradual attrition of the forest. "It has an incredible richness, which should be protected at all costs," says Professor Tomasz Wesołowski, at Wrocław University, who has researched the Białowieża forest for 30 years. He likens it to the Hubble space telescope, which revolutionised astronomy by allowing scientists to peer back in time with unprecedented clarity, but with a key difference. "In the event of damage to [Hubble], it can be replaced. This primeval forest cannot be bought or reconstructed."

Wajrak has another reason why the forest must be protected: "We are a country destroyed by wars and there is not much heritage left, apart from nature. This is the one unique thing we can give to the world."

• This article was amended on 6 April 2012. The original said that the Polish presidency of the EU would begin in January. This has been corrected.